Is something breaking the JavaScript on your site?

Check your web browser debug console. All modern web browser have it including Internet Explorer (IE), Chrome, Firefox, and Safari.

When WordPress was updated to version 4.5 it included a new version of jQuery. That version is far more strict on checking JavaScript syntax. If you have poorly-written JavaScript in a plugin or your WordPress theme you will often see this manifest as a [href#] syntax error in the browser debug console.